const fp = require('lodash/fp')
const cars = [
    {
        name: 'Ferrari FF',
        horsepower: 660,
        dollar_value: 700000,
        in_stock: true
    }, {
        name: 'Spyker C12 Zagato',
        horsepower: 650,
        dollar_value: 648000,
        in_stock: false
    }, {
        name: 'Jaguar XKR-S',
        horsepower: 550,
        dollar_value: 132000,
        in_stock: false
    }, {
        name: 'Audi R8',
        horsepower: 525,
        dollar_value: 114200,
        in_stock: false
    }, {
        name: 'Aston Martin One-77',
        horsepower: 750,
        dollar_value: 1850000,
        in_stock: true
    }, {
        name: 'Pagani Huayra',
        horsepower: 700,
        dollar_value: 1300000,
        in_stock: false
    }
]

//练习1：使用fp.flowRight重新实现isLastInStock
let isLastInStock = function (cars) {
    let last_car = fp.last(cars)
    return fp.prop('in_stock', last_car)
}
let isLastInStock2 = fp.flowRight(fp.prop('in_stock'), fp.last)
console.log(isLastInStock(cars))
console.log(isLastInStock2(cars))

//练习2： 获取第一个car的name
let getFirstName = fp.flowRight(fp.prop('name'), fp.first)
console.log(getFirstName(cars))

//练习3： 使用帮助函数——average重构averageDollarValue
let _average = function (xs) {
    return fp.reduce(fp.add, 0, xs) / xs.length
}
let averageDollarValue = function (cars) {
    let dollar_values = fp.map(function(car) {
        return car.dollar_value
    }, cars)
    return _average(dollar_values)
}
let averageDollarValue1 = fp.flowRight(_average, fp.map((item) => fp.prop('dollar_value', item)))
console.log(averageDollarValue(cars))
console.log(averageDollarValue1(cars))

//练习4： 使用flowRight写一个sanitizeNames()函数，返回下划线连接的小写字符串
let _underscore = fp.replace(/\W+/g, '_')
let sanitizeNames = fp.map(item => fp.flowRight(_underscore, fp.toLower)(item))

let testArray = ["Hello World"]
console.log(sanitizeNames(testArray))
